Direct-injection engines inject fuel at high pressure directly into the engine's combustion chambers. The fuel may be injected via a common fuel rail. The fuel may be pressurized using a high pressure fuel pump, sometimes referred to as a supply pump. The high pressure fuel pump can be a source of undesired engine noise. In particular, the high pressure fuel pump can produce a ticking noise. Research and test data show that the ticking noise occurs as the pump's magnetic solenoid valve (MSV) opens and closes, resulting in an armature-to-stopper impact at closing, or suction valve-to-seat impact at opening. This impact energy not only excites the pump itself but may also be transmitted to the cylinder head through the pump mount. Furthermore, the energy may also travel to other engine components, e.g. the engine block, oil pan, cam covers, front cover, intake and exhaust manifolds. This may have the effect of amplifying the unwanted noise, making it more noticeable especially during engine idle conditions when these other engine components are relatively quiet.
Attempts have been made to reduce the noise emitted from high pressure fuel supply pumps. For example, US Patent Application #20120000445 to BORG et al. discloses a method and control apparatus for controlling a high-pressure fuel supply pump. The disclosed approach decreases a control current of a normally-closed type solenoid-actuated intake valve so that the movement in the opening direction can be decelerated by means of a biasing force at the time of hitting a mechanical stop at the fully-opened position, thereby reducing the impact noise.
The inventors have recognized several potential issues with these approaches. For example, although this approach may reduce impact it may still be great enough to add to unwanted engine noise. Further, it is believed that the decelerated motion may become less synchronized with the moment of impact as the impacted surfaces age and deform over time, and unwanted noise may consequently increase.
In view of these issues, the inventors have taken an approach that reduces valve-to-valve seat impact and may completely eliminate the impact at pump close and open events. Embodiments in accordance with the present disclosure may comprise a valve arrangement including a rotatable disk configured to separate a fuel supply chamber from a pump chamber. There may be one or more holes through the disk designed to correspond to one or more holes in the valve housing. When the valve is at an open position, the disk holes may be configured to align with the valve housing holes to allow fuel flow from the fuel supply chamber to the pump chamber, and vice versa. Since the disk valve may influence fuel flow by rotation, impact between the disk and the valve housing is avoided. In this way the process may generate significantly less noise, and by eliminating any ticking noises the fuel pump may operate almost silently.
Additional examples as per the present disclosure may include a passage separating first and second chambers of the valve arrangement, such as a wall separating a supply chamber and pump chamber. The rotatable disk may be in a sealing arrangement with the wall, and may have one or more holes corresponding to one or more holes in the wall. Gear teeth may be present on at least part of the disk perimeter capable of meshing with a worm screw or similar driving element. The worm may be actuated by a controller and/or a cam or other mechanism.
These embodiments may incorporate methods of establishing a pressure differential between the fuel supply and pump chamber to influence fuel flow when the disk is aligned to allow fuel to pass through. The pump chamber may include a plunger which increases or decreases pressure within the chamber. By adjusting pressure the plunger may also assist in compressing fuel and/or pushing it towards a combustion chamber.
Methods of operation as described may include a controller, attached to a driving element, triggering rotation of the disk based on pre-selected engine operation conditions. Embodiments driven by a worm gear or similar element may have rotation sequences which are influenced by the positioning of a cam. The cam may be responsive to different engine operation conditions, such as engine fuel and/or fuel pressure demand, and may also influence movement of a plunger within the pump chamber.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.